Add an API reference page to the web UI

/apireference lists the REST operations (from the same route list and tool
schemas as the OpenAPI document) with access, parameters and a curl example
for this router. Linked from the API access page.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AeFqV9dZrK6nipHkPfyM4F

pkgs/router-webui/api_test.go

@@ -234,3 +234,25 @@ func TestTokenEditNote(t *testing.T) {
 		t.Fatalf("stale note: %q", note)
 	}
 }
+
+func TestAPIReference(t *testing.T) {
+	a, _ := newTestApp(t)
+	h := a.routes()
+	if rec := do(h, "GET", "/apireference", nil, nil); rec.Code != http.StatusSeeOther {
+		t.Fatalf("without a session: %d", rec.Code)
+	}
+	cookie := login(t, h)
+	rec := do(h, "GET", "/apireference", nil, cookie)
+	body := rec.Body.String()
+	if rec.Code != 200 {
+		t.Fatalf("reference: %d", rec.Code)
+	}
+	for _, rt := range apiRoutes {
+		if !strings.Contains(body, rt.path) {
+			t.Errorf("%s is not on the page", rt.path)
+		}
+	}
+	if !strings.Contains(body, "curl -sk") || !strings.Contains(body, "If-Match") || !strings.Contains(body, "unit=router-pppoe") {
+		t.Errorf("examples missing")
+	}
+}